Good for you for trying to introduce some wet food into your cat's diet! I don't have time right now to get into too many details about how to go about it, so I'm just going to link you to 2 video clips by Dr. Karen Becker that do a good job explaining some methods that work for most cats:
http://healthypets.mercola.com/sites...et-part-1.aspx
http://healthypets.mercola.com/sites...et-part-2.aspx
Main thing is, don't leave dry down for free-feeding and start scheduled mealtimes.